Controlled positioning of arc runners in magnetic field



June 13, 1967 w. A. CARTER 3,325,617

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United States Patent 3,325,617 CGNTROLLED POSITIONHNG 0F ARC RUNNERS INMAGNETIC FIELD William A. Carter, Devon, Pa, assignor to I-T-E CircuitBreaker Company, Philadelphia, Pa., a corporation of Pennsylvania FiledApr. 23, 1965, Ser. No. 450,451 9 Claims. (Cl. 200-147) This applicationis a continuation-in-part of application Ser. No. 87,440, filed Feb. 6,1961 in the name of William A. Carter and assigned to the assignee ofthe instant invention, and now abandoned.

This invention relates primarily to circuit breakers and moreparticularly to the controlled positioning of the arc runners of suchcircuit breaker within the magnetic field generated within the arc chuteof such circuit breakers.

Circuit breakers generally in use in present day switchgear systems aredesigned to include interrupting means which provide rapidextinguishment of electric arcs formed during the tripping operation.The interrupting means of the prior art are designed to include magneticblow-out means for urging electric arcs upward into the interruptingmeans. Such magnetic means include a blow-out coil which is wound aboutan iron core. The iron core surrounds the perimeter of the interruptingmeans and acts to direct the magnetic field generated by the blow-outcoil such that the direction of the magnetic field is transverse to theupwardly moving arc and the vertical faces of the interrupting means.Such apparatus is shown, for example, in FIGURE 6 of United StatesPatent No. 3,070,681, entitled, Face Wound Blow-Out Coil, issued Dec.25, 1962, to J. D. Wood and assigned to the assignee of the instantinvention.

The arc which is formed during the tripping operation of the circuitbreaker is initially drawn between the breaker separating contacts. Thearc then transfers to a pair of spaced parallel arc runners which arepositioned in the interrupting means. In travelling upward along thespaced parallel arc runners, the arc is confronted by a plurality ofspaced parallel arc plates which provide a toruous path for the arcresulting in subsequent cooling and extinguishment thereof.

Prior art circuit breakers of the type described above suffer from aserious disadvantage which the instant invention effectively eliminates.Specifically, and as will be described in further detail, the arcrunners of prior art circuit breakers are positioned within the arcchute at locations which are subjected to high magnitudes of magneticflux, and consequently the ends of a drawn are which are traveling uptheir respective arc runners are subjected to extremely high forceswhich greatly accelerate their travel up the respective arc runners. Theends of the arc arrive at the top of their runners prior to theextinguishment of the arc itself and are forced to linger there for alarge percentage of the total extinguishment time. During this periodthe burning arc ends are concentrated at one point, the result of whichis the liberation of substantial amounts of gaseous are products whichcan destroy adjacent insulated elements.

The instant invention contemplates an arrangement whereby theabove-described prior art problem may be eliminated. Specifically, theinstant invention contemplates placing the arc runners in apredetermined position relative to the blow out coil which substantiallyalters the magnetic flux density affecting the runner surfaces, therebyvarying the magnetic flux affecting the ends of a drawn arc. Thus theends of the arc may not be prematurely accelerated upward along theirrespective arc runners, and therefore the delay between the arrival ofthe ends of the are at the tops of their runners and the finalextinguishment of the arc itself is eliminated. With car such time delayeliminated, the tops of the are are not subjected to the concentratedburning of the ends of the arc and therefore the problem described aboveis eliminated.

Accordingly, it is an object of this invention to provide a novelmagnetic air circuit breaker including a face wound blow-out in whichthe arc runners thereof are positioned in a predetermined relationshipwith respect to the blow-out coil to vary the magnetic flux whichaffects the surfaces of such arc runners.

Another object of the instant invention is to provide a novel magneticair circuit breaker including a face wound blow-out coil in which thearc runners thereof are positioned in a predetermined relationship withrespect to the tblow-out coil in order to retard the movement of theends of a drawn arc upwardly along their respective arc runners.

These and other objects of the invention will become apparent from thefollowing description when taken in conjunction with the followingdrawings, in which:

FIGURE 1 is a perspective view of a circuit breaker in which the instantinvention may find application;

FIGURE 2 is a side plan view of the circuit breaker shown in FIGURE 1;

FIGURE 3 is a top plan view of the circuit breaker shown in FIGURE 1;

FIGURE 4 is a top plan view of a circuit breaker of the prior art andillustrating the positioning of the are runners of such circuit breakerwith respect to the blow-out coil of such circuit breaker;

FIGURE 4a is a top plan view of a circuit breaker similar to the circuitbreaker illustrated in FIGURE 4, but showing the controlled positioningof the arc runners of such circuit breaker with respect to the blow-outcoil of such circuit breaker, such controlled positioning of the arcrunners representing the contribution of the instant invention over theprior art;

FIGURE 4b is a top plan view of a circuit breaker similar to the circuitbreaker shown in FIGURE 1, but illustrating the controlled positioningof the arc runners of such circuit breaker with respect to the blow-outcoil of such circuit breaker, such breaker having no iron core;

FIGURES 5, 5a and 6 are top plan views of circuit breakers within ironcores having alternative configurations; and

FIGURE 7 is a graph showing the magnetic flux distribution obtained bythe circuit breaker shown in FIG- URES 4, 4a, 5, 5a and 6.

Referring now to the drawings, FIGURE 1 shows a circuit breaker 10 whichcomprises upper and lower terminals 11 and 12, respectively, which areconnected to the circuit to be protected.

Although FIGURE 1 shows a circuit breaker for protecting a three-phasesystem, this showing is merely exemplary since my invention willfunction equally as well with either a lesser or greater number ofphases. Terminals 11 and 12 are supported and isolated from one anotherby support means 13. Each lower terminal 12 is connected at its oppositeend to movable bridge 14 (only a portion of which is shown in FIGURE 1).The opposite end of the movable bridge 14 has a main and arcing contactsecured thereto which contacts engage the main and arcing contacts,respectively, mounted to upper terminals 11 (see FIGURE 2).

Interrupting means 15 is operatively positioned with respect to thecooperating contacts of circuit breaker 10 and consists of an arc chute16 which is pivotally supported to support 13 by pivot means 17. Ironstructure 18 which consists of a plurality of U-shaped laminations 19and 2% (see FIGURE 3) surround the mid portion of arc chute 16 and arerigidly secured thereto by fastening means 21. Magnetic core 18 has agap 22 which separates U-shaped laminations 19 and 20. As shown inFIGURE 3, a like gap exists on the opposite face of arc chute 16. Theoperating mechanism (not shown) is mounted in the lower portion 23 ofthe carriage 24 upon which circuit breaker is mounted. Movable bridge 14is connected to the operating mechanism used in lower portion 23 bymeans of push rod 25.

FIGURE 2 shows the interior of circuit breaker 10 which consists of amovable bridge 14 which is pivotally mounted to lower terminal 12 bypivot means 26. Arcing contacts 27 and main contacts 28 are fixedlysecured to the opposite end of movable bridge 14 and are positioned toengage arcing and main contacts 29 and 30, respectively, which areelectrically connected to upper terminal 11.

Rear arc runner 32, which has an inwardly sloping lower portion 32a issecured to are chute 16 in any well known manner. Front are runner 33 ispositioned in the right hand side of arc chute 16 (with respect toFIGURE 2) and has an inwardly sloping portion 34. Conductive strips 35and 36 serve as the path which links front are runner 33 to lowerterminal 12.

Jump gap 31 is secured to arc chute 16 by pin means 31a which alsosecures the lower end of rear arc runner 32. Positioned between arcrunners 32 and 33 are a plurality of arc plates 37 arranged in spacedparallel fashion. Arc plates 37 are supported by a ledge means 38 whichare an integral part of the opposite faces of the interior of arc chute16. It should be noted that arc plates 37 and are runners 32 and 33 maybe supported and mounted by any well known means, such as the meansshown for example in United States Patent ,93 entitled High VoltageCircuit Breakers, issued Sept. 4, 1952, to I. D. Wood, and assigned tothe same assignee as the instant invention, or in United States Patent2,941,060 entitled, Arc Extinguishing Means for High Voltage CircuitBreaker, issued June 14, 1960, to A. S. Caswell, and assigned to thesame assignee as the instant invention. Since the arc plate and arerunner mountings play no part in the novelty of the instant invention,it should be understood that the above references are cited as merelyexemplary.

Mounted immediately above are plates 37 in arc chute 16 are a pluralityof alternately disposed deflecting plates 39 which are positioned andsecured by vertical positioning means 40. The alternate deflecting means39 serve to prevent the commingling and gathering of heated and ionizedgases in the area immediately above the top of arc chute 16 so as toprevent a flash-over from occurring between arc runners 32 and 33immediately above arc plates 37. The structure and operation ofdeflecting plates 39 is more fully explained in United States copendingapplication Ser. No. 779,419, entitled, Alternate Lateral DeflectingMeans for Arc Products, filed Dec. 10, 1958, by William A. Carter, andnow abandoned, and assigned to the same assignee as the instantinvention.

My novel magnetic circuit, however, may be also utilized in arc chutesnot containing deflection plates 39 since they play no part in thenovelty of the instant invention.

Blow-out coils 41 (see FIGURES 2 and 3) are positioned along oppositevertical front faces 16a of arc chute 16. Coils 41 are wound in aconfiguration to encompass contacts 27-30 so that these elements areunder the influence of a strong magnetic field set up by the blow-outcoils 41.

As can be seen in FIGURE 3, the laminations of iron core 18 defineplanes which are parallel to the plane of the paper upon which FIGURE 3is drawn, which planes are transverse to the plane of the blow-out coils41 (extending along the vertical front faces 16a of the arc chute 16).Thus, as can be most clearly seen in FIGURE 3, the plane of the entirecore structure may be thought of as a plane which is transverse to theplane of the blow-out coils 41. Although FIGURE 3 shows the use of aniron core to intensify the magnetic flux within the arc chute,

tribution using the prior art magnetic cores 42 shown in FIGURES 4 and4a. Curve 104 shows the magnetic flux distribution in a circuit breakerhaving no iron core. It should be noted that these curves aresubstantially flat along their length and thus may be said to representa uniform magnetic flux within the area between the arc runners.

FIGURE 4 shows the positioning of the rear and front are runners 320 and330, respectively, with respect to the blow-out coils 41 for the priorart configuration. Such positioning corresponds to the positioning ofarc runners 60 and 62 of the aforementioned Wood Patent 3,070,681,within the area defined by blow-out coil 70. From FIG- URE 7 it can beseen that such positioning results in the surfaces of arc runners 320and 330 being under the influence of the greatest magnitude of magneticflux for curve 101). Note that the magnetic flux shown graphically inFIGURE 7 by the flat portion of curve is approximately 2000 gauss, andthat such magnitude of magnetic flux is influential on the surfaces ofarc runners 320 and 330.

Thus the ends of an are which is drawn between arc runners 320 and 330will be accelerated at a high rate of speed and prematurely arrive atthe tops of these arc runners prior to the extinguishment of the arewhich is being slowed down within the central portion of the arc chute16 by the interposed arc plates 37. The end result is that the ends ofthe are are concentrated at the tops of the arc runners for a time delaywhich corresponds to the movement of the center portion of the arcupwardly into the arc chute to a point at which it can be extinguished.This time delay results in excessive deterioration of the tops of thearc runners and reduces the effective life of the circuit interrupter,as previously discussed.

As can be seen in FIGURES 4a and 4b the instant invention contemplatesthat the arc runners 32 and 33 may be selectively located to utilize thefield that is required by the particular interrupter. That is, when itis desirable to diminish the velocity of one end of an arc, theassociated arc runner may be placed in a low value of magnetic flux.Such embodiment is shown in FIGURES 4a and 4b wherein arc runner 33 ispositioned in a low magnetic field.

FIGURE 7 shows the above described controlled positioning of arc runner33 wherein arc runner 33 is influenced by low values of magnetic flux.Note that the end of curve 100 dips sharply in the region immediatelyadjacent the surfaces of arc runner 33. The affect of this controlledpositioning is to reduce the force on the end of a drawn arc and thusdiminish its velocity up are runner 33, thus preventing prematurearrival of the end of the arc prior to the extinguishment of the arcitself.

On the other hand, if it is desirable to accelerate one end of a drawnarc, the runner can be positioned in a more intense magnetic field. Suchembodiment is shown in FIGURE 4b wherein arc runner 32 is deliberatelymoved toward the center of the arc chute. Such movement is preferablylimited to positions within the range indicated at 308 in FIGURE 7. Itis clear that one would not place arc runner 32 in the prior artposition of arc runner 320, since such positioning would produce theundesirable result discussed above.

A further advantage resulting from the retardation of the ends of theupwardly moving arc is that the center of the arc may move upwardly intothe arc chute faster than the ends of the arc are moving up theirrespective arc runners. This fact allows the arc to be effectivelylengthened and thus aids in extinguishment. Thus, and as shown in FIGURE8, with the arc runners 32 and 33 positioned directly in front of thevertical portions 41a and 41b of blow-out coil 41, so that the magneticflux affecting these runners is at a minimum compared to the flux in thecenter of the arc chute (see FIGURE 7), the roots 401 and 402 of arc 403will progress slower up the chute than the center of the are which isinfluenced by the maximum flux. Hence, the are 403 will be effectivelylengthened and thereby aid extinguishment (the extended length of are403 is to be compared with a length of arc 404 which would exist if theroots of the arc travelled at the same rate as the center of the arc).

It should be noted that either one or both of the arc runners 32 and 33may be positioned in accordance with the teachings of the instantinvention, with the result being a desirable lengthening of the arc.However, in the preferred embodiment, both are runners are so positionedin order to prevent premature arrival of either end of the arc at thetop of its respective runner. Also, the controlled positioning of theare runners in accordance with the teachings of this invent-ion may beaccomplished within an arc chute which utilizes only one blow-out coil41, face Wound on one surface 16a of the arc chute l6.

FIGURES 5, 5a and 6 show the controlled positioning of arc runners 32and 33 relative to the blow-out coils 41 in circuit breakers utilizingmagnetic core structures of varying configuration. As is explained incopending application Ser. No. 452,453 filed Apr. 23, 1965 in the nameof William A. Carter and assigned to the assignee of the instantinvention, the various iron core configurations produce unexpectedmagnetic and electrical results which improve the operatingcharacteristics of the circuit breakers in which they are used. For thepurposes of this invention it is sufficient to note that the arc runners32 and 33 in FIGURES 5, 5a and 6 may be selectively positioned withrespect to the blow-out coils 41 to achieve the results discussedimmediately above. From FIGURE 7 it can be seen that the ends of curves100, 101, 102, 103 and 104 (which curves correspond to the iron coreconfiguration of FIGURES 4 and 4a, 5, 5a, 6, and 4b, respectively) dipsharply in the regions immediately adjacent the arc runners 32 and 33.Thus it is apparent that the controlled positioning aspect of the arcrunners in accordance with the teachings of the instant invention mayfind application in combination with the advantageous iron coreconfiguration of the aforementioned copending application.

Thus there has been described a novel magnetic air circuit breaker whichincludes a face wound blow-out coil. Furthermore, by means of acontrolled spacial orientation of the arc runners of such circuitbreaker with respect to the face wound blow-out coil, the magnetic fluxand resultant force appearing in the vicinity immediately adjacent thearc runners may be substantially varied so that the velocity of the endsof an are moving upwardly through the associated arc chute may besubstantially reduced to prevent lingering of the ends of the arc at thetops of their respective arc runners.

Although I have described my invention with a certain degree ofparticularity, it is to be understood that the present disclosure hasbeen made only by way of example and that numerous changes in theexamples of construction and the combination and arrangement of partsmay be resorted to without departing from the sphere and scope of theinvention as hereinafter claimed.

What is claimed is:

1. A circuit breaker comprising a pair of cooperating contacts, asubstantially rectangular arc chute positioned to extinguish an aredrawn between said contacts upon separation thereof, said arc chutehaving a pair of opposite interior ends and first and second oppositefaces joining said opposite interior ends, blow-out means energized bysaid are for urging said arc into said are chute, said blow-out meansincluding a face wound blow-out coil, said blow-out coil beingpositioned along said first face of said arc chute, a first and secondarc runner positioned at said opposite interior ends of said arc chute,said blow-out means generating a magnetic field within said arc chutewhen said blow-out coil is energized, said magnetic field beingsubstantially less in vicinities adjacent said opposite interior ends ofsaid are chute than in a vicinity intermediate said opposite interiorends of said arc chute, at least one of said arc runners beingselectively positioned within said arc chute within one of saidvicinities which are adjacent one of said opposite interior ends of saidare chute, whereby said one of said arc runners will be subjected to amagnetic field which is substantially less than the magnetic field insaid vicinity intermediate said opposite interior ends.

2. A circuit breaker comprising a pair of cooperating contacts, asubstantially rectangular arc chute positioned to extinguish an arcdrawn between said contacts upon separation thereof, said arc chutehaving a pair of opposite interior ends and first and second oppositefaces joining said opposite interior ends, blow-out means energized bysaid are for urging said arc into said arc chute, said blow-out meansincluding a face wound blow-out coil and iron core, said blow-out coilbeing positioned along said first face of said are chute, said iron corebeing substantially rectangular in shape and being positioned tosurround the outer perimeter of said are chute, the plane of said ironcore being transverse to the plane of said blow-out coil, a first andsecond arc runner positioned at said opposite interior ends of said arechute, said blow-out means generating a magnetic field within said arechute when said blow-out coil is energized, said mag netic field beingsubstantially less in vicinities adjacent said opposite interior ends ofsaid arc chute than in a vicinity intermediate said opposite interiorends of said are chute, at least one of said are runners beingselectively positioned within said are chute within one of saidvicinities which are adjacent one of said opposite interior ends of saidare chute, whereby said one of said are runners will be subjected to amagnetic field which is substantially less than the magnetic field insaid vicinity intermediate said opposite interior ends.

3. A circuit breaker comprising a pair of cooperating contacts, asubstantially rectangular arc chute positioned .to extinguish an aredrawn between said contacts upon separation thereof, said are chutehaving a pair of opposite interior ends and first and second oppositefaces joining said opposite interior ends, blow-out means energized bysaid arc for urging said are into said arc chute, said blowout meansincluding a face wound blow-out coil, said blow-out coil beingpositioned along said first face of said arc chute, a first and secondarc runner positioned at said opposite interior ends of said are chute,said blow-out means generating a magnetic field within said are chutewhen said blow-out coil is energized, said magnetic field beingsubstantially less in vicinities adjacent said opposite interior ends ofsaid arc chute than in a vicinity intermediate said opposite interiorends of said arc chute, said first and second arc runner beingrespectively selectively positioned within said arc chute within saidvicinities which are adjacent said opposite interior ends of said arcchute, whereby said arc runners will be subjected to magnetic fieldswhich are substantially less than the magnetic field in said vicinityintermediate said opposite interior ends.

4. A circuit breaker comprising a pair of cooperating contacts, asubstantially rectangular arc chute positioned to extinguish an arcdrawn between said contacts upon separation thereof, said arc chutehaving a pair of opposite interior ends and first and second oppositefaces joining said opposite interior ends, blow-out means energized bysaid arc for urging said are into said are chute, said blow-out meansincluding a face wound blow-out coil and an iron core, said blow-outcoil being positioned along said first face of said are chute, said ironcore being substantially rectangular in shape and being positioned tosurround the outer perimeter of said are chute, the plane of said ironcore being transverse to the plane of said blow-out coil, a first andsecond arc runner posi tioned at said opposite interior ends of said arechute, said blow-out means generating a magnetic field within said arcchute when said blow-out coil is energized, said magnetic field beingsubstantially less in vicinities adjacent said opposite interior ends ofsaid are chute than in a vicinity intermediate said opposite interiorends of said are chute, said first and second arc runner beingrespectively selectively positioned within said arc chute within saidvicinities which are adjacent said opposite interior ends of said arcchute, whereby said are runners will be subjected to magnetic fieldswhich aresubstantially less than the magnetic field in said vicinityintermediate said opposite interior ends.

5. A circuit breaker comprising a pair of cooperating contacts, asubstantially rectangular arc chute positioned to extinguish an arcdrawn between said contacts upon separation thereof, said arc chutehaving a pair of opposite interior ends and first and second oppositefaces joining said opposite interior ends, blow-out means energized bysaid are for urging said are into said are chute, said blow-out meansincluding a face wound blow-out coil, said blow-out coil beingpositioned along said first face of said are chute, said blow-out coilhaving first and second portions parallel to said first face of said arechute, said first and second portions of said blow-out coil beingpositioned at said opposite interior ends of said are chute, saidblow-out coil generating a magnetic field within said are chute whensaid blow-out coil is energized, said magnetic field being substantiallyless in vicinities adjacent said opposite interior ends of said arechute than in a vicinity intermediate said opposite interior ends ofsaid are chute, a first and second arc runner positioned at saidopposite interior ends of said are chute, a portion of at least one ofsaid are runners being positioned within a plane which is transverse tothe plane of said blow-out coil and which intersects said first portionof said blow-' out coil, the exact positioning of said portion of saidone of said are runners within a plane which is transverse to the planeof said blow-out coil and which intersects said first portion of saidblow-out coil minimizing the magnetic field intensity which affects thesurface of said one of said are runners when said blow-out means isenergized.

6. A circuit breaker comprising a pair of cooperating contacts, asubstantially rectangular arc chute positioned to extinguish an aredrawn between said contacts upon separation thereof, said arc chutehaving a pair of opposite interior ends and first and second oppositefaces joining said opposite interior ends, blow-out means energized bysaid are for urging said are into said arc chute, said blow-out meansincluding a face wound blow-out coil and an iron core, said blow-outcoil being positioned along said first face of said are chute, said ironcore being substantially rectangular in shape and being positioned tosurround the outer perimeter of said are chute, the plane of said ironcore being transverse to the plane of said blow-out coil, said blow-outcoil having first and second portions extending through said iron coreparallel to said first face of said are chute, said first and secondportions of said blow-out coil being positioned at said oppositeinterior ends of said are chute, said blow-out coil generating amagnetic field within said arc chute when said blow-out coil isenergized, said magnetic field being substantially less in vicinitiesadjacent said opposite interior ends of said are chute than in avicinity intermediate said opposite interior ends of said are chute, afirst and second arc runner positioned at said opposite interior ends ofsaid are chute, portions of said first and second arc runners beingpositioned within planes which are transverse to the plane of saidblow-out coil and which intersect said first and second portions of saidblow-out coil respectively, the exact positioning of said portions ofsaid first and second arc runners within planes which are transverse tothe plane of said blow-out coil and which intersect said first andsecond portions of said blow-out coil, respectively, minimizing themagnetic flux which afi'ects the surface of said first and second arcrunner when said blow-out means is energized.

7. A circuit breaker comprising a pair of cooperating contacts, asubstantially rectangular arc chute positioned to extinguish an arcdrawn between said contacts upon separation thereof, said arc chutehaving a pair of opposite interior ends and first and second oppositefaces joining said opposite interior ends, blow-out means energized bysaid are for urging said are into said arc chute, said blowout meansincluding a first and second face wound blowout coil, said blow-outcoils being positioned in planes along said opposite faces of said arechute, each of said first and second blow-out coils having first andsecond portions, respectively, said first and second portions of saidfirst and second blow-out coils being positioned at said oppositeinterior ends of said are chute, a front and rear arc runner positionedat said opposite interior ends of said are chute, said blow-out meansgenerating a magnetic field within said are chute when said blow-outcoils are energized, said magnetic field being substantially less invicinities adjacent said opposite interior ends of said are chute thanin a vicinity intermediate said opposite interior ends of said arcchute, at least one of said are runners being selectively positionedwithin said are chute within one of said vicinities which are adjacentone of said opposite interior ends of said are chute, whereby said oneof said arc runners will be subjected to a magnetic field which issubstantially less than the magnetic field in said vicinity intermediatesaid opposite interior ends.

8. A circuit breaker comprising a pair of cooperating contacts, asubstantially rectangular arc chute positioned to extinguish an arcdrawn between said contacts upon separation thereof, said arc chutehaving a pair of'opposite interior ends and first and second oppositefaces joining said opposite interior ends, said blow-out means energizedby said arc for urging said are into said are chute, said blow-out meansincluding a first and second face wound blow-out coil and an iron core,said blow-out coils being positioned along said opposite faces of saidare chute, said iron core being substantially rectangular in shape andbeing positioned to surround the outer perim eter of said are chute, theplane of said iron core being transverse to the plane of said blow-outcoils, each of said first and second blow-out coils having first andsecond portions respectively which extend through said iron coresubstantialily transverse to the plane of said iron core, said first andsecond portions of said first and second blowout coils being positionedat said opposite interior ends of said are chute, said blow-out coilsgenerating a magnetic field within said are chute when said blow-outcoils are energized, said magnetic field being substantially less invicinities adjacent said opposite interior ends of said are chute thanin a vicinity intermediate said opposite interior ends of said arechute, a front and rear arc runner positioned at said opposite interiorends of said are chute, at least one of said front and rear arc runnershaving a portion thereof positioned in a plane extending between thefirst portion of said first blow-out coil and the first portion of saidsecond blow-out coil, the exact positioning of said one of said arcrunners within a plane joining the first portions of said first andsecond blow-out coils minimizing the magnetic flux which affects thesurfaces of said one of said arc runner when said blow-out means isenergized.

9. A circuit breaker comprising a pair of cooperating contacts, asubstantially rectangular arc chute positioned to extinguish an arcdrawn between said contacts upon separation thereof, said are chutehaving a pair of opposite interior ends and first and second oppositefaces joining said opposite interior ends, blow-out means energized bysaid arc for urging said arc into said are chute, said blow-out meansincluding a first and second face Wound blow-out coil and an iron core,said blow-out coils being positioned along said opposite faces of saidare chute, said iron core being substantially rectangular in shape andbeing positioned to surround the outer perimeter of said arc chute, theplane of said iron core being transverse to the plane of said blow-outcoils, each of said first and second blow-out coils having first andsecond portions, respectively, which extend through said iron coresubstantially transverse to the plane of said iron core, said first andsecond portions of said first and second blow-out coils being positionedat said opposite interior ends of said are chute, said blow-out coilsgenerating a magnetic field within said arc chute when said blow-outcoils are energized, said magnetic field being substantially less invicinities adjacent said opposite interior ends of said arc chute thanin a vicinity intermediate said opposite interior ends of said arcchute, a front and rear arc runner positioned at said opposite interiorends of said are chute, said front are runner having a portion thereofpositioned in a plane extending 10 between the first portion of saidfirst blow-out coil and the first portion of said second blow-out coil,and said rear arc runner having a portion thereof positioned in a planeextending between the second portion of said first'blow-out coil andsaid second portion of said second blow out coil, the exact positioningof said are runners Within the planes joining the respective first andsecond portions of said first and second blow-out coils minimizing themagnetic field which affects the surfaces of said front and rear arcrunners when said blow-out means is energized.

References Cited UNITED STATES PATENTS 2,337,949 12/ 1943 Walle 2001473,033,963 5/1962 Bohn 200147 3,070,681 12/1962 Wood 200-147 3,155,80111/1964 Pokorny 200147 FOREIGN PATENTS 1,357,564 2/1964 France.

ROBERT K. SCHAEFER, Primary Examiner. ROBERT S. MACON, Examiner.

1. A CIRCUIT BREAKER COMPRISING A PAIR OF COOPERATING CONTACTS, ASUBSTANTIALLY RECTANGULAR ARC CHUTE POSITIONED TO EXTINGUISH AN ARCDRAWN BETWEEN SAID CONTACTS UPON SEPARATION THEREOF, SAID ARC CHUTEHAVING A PAIR OF OPPOSITE INTERIOR ENDS AND FIRST AND SECOND OPPOSITEFACES JOINING SAID OPPOSITE INTERIOR ENDS, BLOW-OUT MEANS ENERGIZED BYSAID ARC FOR URGING SAID ARC INTO SAID ARC CHUTE, SAID BLOW-OUT MEANSINCLUDING A FACE WOUND BLOW-OUT COIL, SAID BLOW-OUT COIL BEINGPOSITIONED ALONG SAID FIRST FACE OF SAID ARC CHUTE, A FIRST AND SECONDARC RUNNER POSITIONED AT SAID OPPOSITE INTERIOR ENDS OF SAID ARC CHUTE,SAID BLOW-OUT MEANS GENERATING A MAGNETIC FIELD WITHIN SAID ARC CHUTEWHEN SAID BLOW-OUT COIL IS ENERGIZED, SAID MAGNETIC FIELD BEINGSUBSTANTIALLY LESS IN VINCINITIES ADJACENT SAID OPPOSITE INTERIOR ENDSOF SAID ARC CHUTE THAN IN A VICINITY INTERMEDIATE SAID OPPOSITE INTERIORENDS OF SAID ARC CHUTE, AT LEAST ONE OF SAID ARC RUNNERS BEINGSELECTIVELY POSITIONED WITHIN SAID ARC CHUTE WITHIN ONE OF SAIDVICINITIES WHICH ARE ADJACENT ONE OF SAID OPPOSITE INTERIOR ENDS OF SAIDARC CHUTE, WHEREBY SAID ONE OF SAID ARC RUNNERS WILL BE SUBJECTED TO AMAGNETIC FIELD WHICH IS SUBSTANTIALLY LESS THAN THE MAGNETIC FIELD INSAID VICINITY INTERMEDIATE SAID OPPOSITE INTERIOR ENDS.